Zephronia ovalis Gray, 1832.

59 species, including the two new species described here.

Cambodia, China (including Hong Kong), India (NE), Indonesia, Laos, Malaysia, Myanmar, Nepal, Singapore, Thailand, and Vietnam.

Zephronia is one of the most species-rich genera within Zephroniidae, currently comprising 59 described species. Many species remain insufficiently studied, especially type re-examinations are lacking, with many known only from females, particularly those from Myanmar, Borneo, Sumatra, and India. Consequently, the genus is in urgent need of a revision, and some species currently placed in Zephronia may be transferred to separate genera in the future.

Zephronia differs from other genera of Zephroniinae by the following combination of characters: endotergum weakly modified; posterior margin usually flat (rarely modified); outer area without setae; marginal bristles arranged in 1–5 rows; middle area often with a single row of circular cuticular impressions; tarsi of leg pairs 5–21 usually with more than one apical spine (rarely with a single apical spine) and several ventral spines; male anterior telopods with four podomeres distal to syncoxite; telopoditomere 2 bearing a large, curved process forming a clamp-like structure; telopoditomeres 3 and 4 simple; male posterior telopods with four telopoditomeres; process of telopoditomere 2 slender and apically curved; telopoditomeres 3 and 4 with a membranous ledge; telopoditomere 3 with a row of large, crenulated, sclerotised teeth; telopoditomere 4 with one or two sclerotised spines; female vulvae conspicuous and slender, operculum usually rounded.

See more recent diagnoses for Zephronia sensu lato and Zephronia sensu stricto in Srisonchai et al. (2024).

• 18 ♂♂ 33 ♀♀ (MZKKU); Thailand, Khon Kaen Province, Mueang District, Thung Setthi Temple; 16°24'33"N, 102°53'05.7"E; ca. 150 m a.s.l.; 12 July 2022; leg. C. Wilaisorn and MZKKU students; • 5 ♂♂ 7 ♀♀ (MZKKU); Thailand, Buri Ram Province, Khu Mueang District, Dong Kheng rubber plantation; 15°19'46"N, 103°00'59"E; ca. 159 m a.s.l.; 6 July 2022; leg. C. Wilaisorn and MZKKU students; • 4 ♂♂ 2 ♀♀ (MZKKU); Thailand, Buri Ram Province, Mueang District, Khao Kradong; 14°56'21.5"N, 103°05'28.8"E; ca. 213 m a.s.l.; 10 September 2023; leg. C. Wilaisorn and MZKKU students; • 3 ♀♀ (MZKKU); Thailand, Buri Ram Province, Mueang District, Ban Khok Ta Sing Waterfall; 14°55'22.8"N, 103°06'57.9"E; ca. 180 m a.s.l.; 5 June 2022; leg. C. Wilaisorn and MZKKU students. • 12 ♂♂ 21 ♀♀ (MZKKU); Thailand, Buri Ram Province, Khu Mueang District, Non Somboon Monastery; 15°16'32"N, 102°59'13"E; ca. 200 m a.s.l.; 31 July 2022; leg. C. Wilaisorn and MZKKU students.

In Z. dawydoffi, the Tömösváry’s organ is positioned at the brim rather than inside the antennal groove (Fig. 3B, C), confirming its placement within Zephronia s.s. species group (see Semenyuk et al. 2018), which is also supported by genetic evidence (Fig. 1). Z. dawydoffi differs from all other Zephronia s.s. species, except for Z. laotica, Z. ovalis, and Z. siamensis, in the presence of colour patches on the tergites as well as in the posterior margin of the endotergum which is modified (Fig. 22A, B), and the lack of an apical spine in the third leg-pair. It differs from Z. laotica, Z. ovalis, and Z. siamensis in the shape of the anterior telopods with the process of telopoditomere 2 broadened, shorter than telopoditomere 3+4 (Figs 6C, 6F, 23A–C), the process of telopoditomere 2 of the posterior telopods long (Figs 6B, 23D, 23E), and the presence of two locking carinae on the underside of anal shield (Fig. 4F; except for Z. laotica). The genetic differentiation of the 658 bp COI fragment between Z. dawydoffi and other Zephronia ranged from 8.68 to 21.92%.

CAMBODIA (Ream, Sre Umbell; Kampot, Kampong Speu).

Measurements. Males: body length = 10.5–18.8 mm; width (broadest), of thoracic shield = 5.3–8.6 mm, of tergite 7 = 5.6–9.3 mm; highest of thoracic shield = 3.1–5.5 mm, of tergite 7 = 3.3–6.9 mm. Females: body length = 11.5–22.0 mm; width (broadest), of thoracic shield = 5.8–10.6 mm, of tergite 7 = 6.4–11.7 mm; highest of thoracic shield = 4.0–7.1 mm, of tergite 7 = 4.4–8.2 mm.

Colouration (Fig. 2A–G). Live specimens dark green with yellow semicircular colour markings. Head and collum dark green. Thoracic shield and tergites dark green (rarely greenish-brown or dark brown), each with yellowish brown posterior bands and two yellow (rarely pale yellow) dorsal patches per tergite. Anal shield dark green with a conspicuous yellow patch anteriorly, and orangish brown on posterior margin. Antenna and legs green. Venter pale brown. Preserved specimens in 95% ethanol after 1.5 years changed to brownish green, some faded to yellowish green.

Head (Fig. 3B–D). Trapeziform, broad, stout; densely setose over entire surface including mouthparts. With 77–93 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.

Antennae (Fig. 3B, C, E, F). Short and stout; emerging from sides of head, covered by noticeable long setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 > 4 = 3 > 2 > 1. Antennomere 6 flattened, axe-shaped; with sensilla basiconica around apical disc. Apical disc flat; with 59–73 apical cones in males, and 44–62 apical cones in females.

Epipharynx (Fig. 3K). Apically with a triangular projected central tooth (ct); with conspicuous inner tooth; inner area with a row of triangular fringed spines (rsp); outer area with several slender external teeth (et).

Gnathochilarium (Fig. 3G–J). Lamellae linguales (ll) rectangular, apically concave; covered by long setae. Central pads (Cp) modified; with two types of sensory cones (sc), first type small without tubercle apically, second type larger with a concave pad apically containing a single internal tubercle. Stipites (st) robust, with dense and long setae, located laterally to lamellae linguales. Mentum (me) broad and fused, densely setose. Lateral palpi inconspicuous. Inner palpi (ip) with numerous cylindrical sensory cones (sc) located in single field, each cone concave apically and containing a single internal tubercle.

Mandibles (gnathal lobe) (Fig. 3L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 4–5 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small slender teeth. Molar plate (mp) relatively flat. Condylus (co) conspicuous, apically with a single ridge.

Tegument (Figs 2A–G, 4). Glabrous; collum, thoracic shield, tergites and anal shield covered by tiny setae; each seta emerged from a pit. Tergites and anal shield sparsely setose anteriorly and without setae posteriorly.

Collum (Fig. 3A). Subsemicircular; lateral edges triangular, blunt; with a few long setae.

Thoracic shield. Anterior margin with shallow canal covered with a few scattered long setae, with 5–7 small keels.

Midbody tergite (Fig. 4A–C). Dorso-anterior margin with a row of circular impressions and small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrally.

Anal shield (Fig. 4E–G). Sexually dimorphic, females well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and small tubercles. Inner area with a shallow groove, separated from margin by a row of crenate barriers. Underside with two dark locking carinae; length of each locking carina as long as those of tergites; densely setose especially on lateral margin.

Endotergum of thoracic shield and midbody tergite (Fig. 22A, B). Thoracic shield similar to midbody tergite. Posterior margin (pm) distinctly modified, with rectangular projections, length of each projection being longer than height. Outer area (oa) with several small denticles. Marginal bristles arranged in two rows; tips of the longest bristles not reaching to posterior margin. Middle area (ma) with a single row of oval cuticular impressions (cp); distance between each impression almost twice as long as individual diameter. Cuticular impressions of thoracic shield shallower than those of midbody tergite. Inner area (ia) with long setae.

Pleurite (laterotergite) (Fig. 4H, I). Densely setose. First pleurite boomeranglike, with pointed edge, reaching towards paratergite. Pleurite 2 slightly widened. The remaining pleurites flat, rectangular.

Subanal plate of female (Fig. 4D). Densely setose; wide; triangular; apical margin weakly concave, narrow.

Stigmatic plates (Fig. 5A). First stigmatic plate quite slender, flat antero-posteriorly; semicircular; apex round. Second stigmatic plate in both sexes triangular.

Legs (Fig. 5). All podomeres densely setose. Coxa (cx) large, as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with large and serrated processes. Prefemur wide, stout; apico-mesally without projection. Femur (fe) slightly long, 1.5 × longer than prefemur; with conspicuous long ridge (rdg); apico-mesally with inconspicuous projection; mesal margin dentate, with seven or eight small triangular microscopic spines (sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, shorter than femur+postfemur; first three leg-pairs without an apical spine; leg-pair 1 with 1–3 ventral spines; leg-pair 2 with two or three ventral spines; leg-pair 3 with 3–5 ventral spines; leg pair 4–21 with 6–9 ventral spines and two or three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal, with small notch at base.

Male sexual characters (Fig. 5B). Gonopore surrounded by long setae; covered with a divided, sclerotised plate. Apical part of coxa 2 without membranous process.

Anterior telopods (Figs 6A, 6C, 6F, 23A–C). Consisting of four telopoditomeres. First telopoditomere conspicuous, rectangular, slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; shorter than combination of telopoditomeres 3 and 4 (= movable finger); clearly seen in posterior view; strongly curved toward midway of movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 long and slender; twice as long as telopoditomere 4; partly demarcated from telopoditomere 4 by shallow suture (rarely fused with telopoditomere 4); inner margin with single spine; apically with five or six small crenulated teeth (cr-t) and two conspicuous spines. Telopoditomere 4 tip obtuse. All telopoditomeres densely setose, except for basal part of telopoditomere 1 and apical part of immovable finger.

Posterior telopods (Figs 6A–E, 6G, 23D, 23E). Consisting of four telopoditomeres. First telopoditomere swollen, broad; as wide as long. Telopoditomere 2 large and slender. Process of telopoditomere 2 (= immovable finger) quite long, 2.5 × longer than wide; shorter than a combination of telopoditomeres 3 and 4 (= movable finger); apically obtuse, slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; 2.5 × longer than wide; with a large membranous ledge and single spine at inner margin; posteriorly with a row of nine or ten crenulated teeth (cr-t). Telopoditomere 4 short; 2.5 × shorter than telopoditomere 3; 1.5 × longer than wide; tip tapering; inner margin with two long spines located on a large membranous ledge. Telopoditomeres 1 and 2 covered by long setae anteriorly, sparse setae posteriorly. Telopoditomere 3 sparsely setose at inner margin. Telopoditomere 4 glabrous. Inner horns densely setose, swollen at base; tips pointed, directed posteriad.

Female sexual characters (Fig. 5C). Vulva conspicuous, large, with a few long setae; covering more than half of coxa; located at mesal margin; extending mesally to base of prefemur. Operculum (op) round and slender, rectangular; tip round. Bursa (bu) large, fused into triangular shape, clearly separated from operculum by triangular groove. Apical part of coxa 2 without coxal process.

Variation in body colouration and pattern was observed among specimens. Most individuals displayed dark green tergites, while others exhibited greenish-brown or dark brown tones. Typically, two yellow patches were present on dorsal tergites, though in some specimens these patches appeared faded or paler in colour. The patch shapes also varied, most commonly forming two semicircular markings (Fig. 2A, C, F). In addition, telopoditomeres 3 and 4 of anterior telopods are only partly demarcated in most individuals (Fig. 23A–C), but in some specimens appear completely fused (Fig. 6A, C).

Morphological differences were observed between Thai specimens and the original description by Attems (1953), as well as in comparison with the syntypes deposited in the NHMW. The body size of the type specimens was between 11.0–13.0 mm in length and 5.8–6.0 mm in width, whereas the Thai specimens were larger, with a range of 10.5–22.0 mm in length and 5.6–11.7 mm in width. The thoracic shield of the Thai individuals bears 5–7 weak keels, which are absent from the type description. Furthermore, the posterior margin of the endotergum is described as flat in the type material, but appears modified in the Thai specimens. In the original description, telopoditomeres 3 and 4 of the anterior telopods are fused together, while those of Thai specimens were usually separated by a shallow suture, with only a very few specimens showing a complete fusion. Similarly, telopoditomere 2 of posterior telopods was described as having a single membranous lobe, while the Thai material consistently exhibits two lobes (like most species in the genus). These differences are interpreted as intraspecific variation within the species. In addition, some apparent discrepancies between the type specimens and the Thai material likely result from differences in observational resolution and the use of modern imaging techniques, which allow finer morphological details to be detected.

Zephronia dawydoffi in Thailand is currently known from two provinces in the northeastern region: four localities in the Buri Ram Province and only one locality in the Khon Kaen Province (Fig. 24). This species inhabits agricultural areas, particularly rubber plantations characterised by tall trees, limited sunlight, and fine soil. Specimens were primarily collected during the day, typically found sheltering beneath leaf litter piles (Fig. 2H, I).

Compared with its type locality in southern Cambodia, the known distribution of Z. dawydoffi is extended into Thailand, representing a geographic range spanning approximately 300–700 km.

• 10 ♂♂ 7 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Mae Lamoon Durian plantation; 14°33'00"N, 104°31'51"E; ca. 228 m a.s.l.; 29 July 2022; leg. C. Wilaisorn and MZKKU students; • 10 ♂♂ 12 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Kantrom Tai Temple; 14°34'32"N, 104°20'33"E; ca. 188 m a.s.l.; 6 October 2024; leg. C. Wilaisorn and MZKKU students; • 2 ♀♀ (MZKKU); Thailand, Si Sa Ket Province, Khun Han District, Ta Nuan Rubber plantation; 14°33'47.9"N, 104°21'24.2"E; ca. 180 m a.s.l.; 10 June 2023; leg. C. Wilaisorn and MZKKU students.

The position of the Tömösváry’s organ is located at the brim rather than inside the antennal groove (Fig. 8B, C), confirming the placement of Z. laotica as a member of Zephronia s.s. species group. The presence of colour patches on tergites, as well as a modified posterior margin of the endotergum, and the lack of an apical spine in the third leg-pair are three characters only shared with Z. dawydoffi, Z. ovalis, and Z. siamensis. Z. laotica differs from them in the combination of the following characters: process of telopoditomere 2 of anterior telopods wide (Figs 11F, 23F, 23H); process of telopoditomere 2 of posterior telopods long and swollen (Figs 11B, 23I, 23J); two locking carinae on the underside of the anal shield (Fig. 9F) (except for Z. dawydoffi). The genetic differentiation between Z. laotica and other Zephronia species ranged from 12.79 to 22.98% of COI sequences.

LAOS, Champasak Province, east of Mekong, Garden of Erawan Riverside Hotel.

Measurements. Males: body length = 10.2–15.2 mm; width (broadest), of thoracic shield = 5.2–7.9 mm, of tergite 7 = 5.5–8.1 mm; highest of thoracic shield = 4.4–6.6 mm, of tergite 7 = 3.8–6.1 mm. Females: body length = 11.4–15.5 mm; width (broadest), of thoracic shield = 5.8–10.6 mm, of tergite 7 = 6.2–11.1 mm; highest of thoracic shield = 4.0–7.8 mm, of tergite 7 = 4.3–8.1 mm.

Colouration (Fig. 7A–I). Specimens in life greenish brown or yellowish brown. Thoracic shield and tergites greenish brown, with pale brown posterior bands. Some individuals with two triangular yellow dorsal patches per tergite. Anal shield brown, posterior margin pale brown. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol changed to dark brown after two years of preservation.

Head (Fig. 8B–D). Trapeziform, broad, short; sparsely setose; anterior part and especially mouthparts densely setose. With 66–89 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.

Antennae (Fig. 8B, C, E, F). Short and stout; emerging from sides of head, covered by dense setae; last antennomere reaching back posteriorly to leg pair 3. Lengths of antennomeres in descending order: 6 > 5 > 4 > 3 = 2 = 1. Antennomere 6 flattened, axe-shaped; with a few sensilla basiconica around apical disc. Apical disc flat; with 45–83 apical cones in males, and 41–50 apical cones in females.

Epipharynx (Fig. 8K). Apically with a single triangular central tooth (ct); in the middle with a conspicuous, long, and slender inner tooth; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).

Gnathochilarium (Fig. 8G–J). Lamellae linguales (ll) rectangular, slightly concave; covered by long setae. Central pads (Cp) modified, with two types of sensory cones (sc), first small without tubercle apically, second one larger with a concave pad apically containing a single internal tubercle. Stipites (st) large and thick, with dense and long setae; located laterally to lamellae linguales. Mentum (me) broad and fused, with dense and long setae. Lateral palpi inconspicuous. Inner palpi (ip) with numerous sensory cones (sc) located in a single field, each cone concave apically and containing a single internal tubercle.

Mandibles (gnathal lobe) (Fig. 8L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 4–5 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small, slender teeth. Molar plate (mp) relatively flat. Condylus (co) conspicuous; apically with a single ridge.

Tegument (Figs 7A–I, 9). Quite dull; collum, thoracic shield, tergites and anal shield covered by golden setae; each seta emerged from a pit. Anterior margins of tergites and anal shield with fewer setae than posterior one. Posterior rim with bare setae dorsally and ventrally.

Collum (Fig. 8A). Subsemicircular; lateral edges triangular, with sparse setae.

Thoracic shield. Anterior margin with shallow canal covered by numerous long setae; with 5–8 conspicuous keels.

Midbody tergite (Fig. 9A–C). Dorso-anterior margin with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.

Anal shield (Fig. 9E–G). Slightly sexually dimorphic, females well-rounded, males rectangular and slender. Sparsely setose. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from margin by a row of crenate barriers. Underside with two dark locking carinae; twice as long as those of tergites when combined.

Endotergum of thoracic shield and midbody tergite (Fig. 22C, D). Thoracic shield slightly different from midbody tergite. Posterior margin (pm) regularly flat in thoracic shield while midbody tergite modified with rectangular projection, length of each projection being longer than height. Both thoracic shield and midbody tergite; outer area (oa) with several small denticles; marginal bristles arranged in 1–2 rows, tips of the longest bristles almost not extending over posterior margin; middle area (ma) with a row of oval cuticular impressions (cp), distance between each impression almost the same as individual diameter; inner area (ia) with a few long setae.

Pleurite (laterotergite) (Fig. 9H, I). Densely setose. First pleurite boomeranglike, tip attenuated and pointed. Pleurite 2 wide, tip more rounded. Pleurites 3–12 broad and wide; flat; rectangular; tip reduced in size, forming a small process.

Subanal plate of female (Fig. 9D). Densely setose; wide; triangular; apical margin round and narrow.

Stigmatic plates (Fig. 10A). First stigmatic plate slender; slightly attenuate; apex round, slightly curved towards coxa. Second stigmatic plate in both sexes swollen; shorter than first one; tip without curve.

Legs (Fig. 10). All podomeres densely setose. Coxa (cx) large; first and second leg-pairs without coxal process; leg-pairs 3–21 with serrated processes. Prefemur (pre) rectangular; with short ridge (rdg); apico-mesally with a very weak projection; mesal margin without triangular spines. Femur (fe) long; 1.5 × longer than prefemur; with conspicuous ridge (rdg); apico-mesally with a strong projection; mesal margin dentate, with 12–16 small triangular microscopic spines. Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first three leg-pairs without an apical spine; leg-pair 1 with one or two ventral spines; leg-pair 2 with two or three ventral spines; leg-pair 3 with 3–5 ventral spines; leg pair 4 and 5 with five or six ventral spines and one or two apical spines; leg pairs 6–18 with 6–8 ventral spines and two apical spines; leg pair 19–21 with 5–7 ventral spines and one or two apical spines. In leg 10, femur 1.5 × and tarsus 2.5 × longer than wide. Claw normal; with small notch at base.

Male sexual characters (Fig. 10B). Gonopore triangular; covered with an undivided, triangular, sclerotised plate. Apical part of coxa 2 without membranous process.

Anterior telopods (Figs 11A, 11C, 11F, 11G, 23F–H). Consisting of four telopoditomeres. First telopoditomere rectangular; slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) wide; shorter than movable finger (= combination of telopoditomeres 3 and 4); clearly seen in posterior view; strongly curved toward movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 slender; almost twice as long as telopoditomere 4; clearly demarcated from telopoditomere 4 by shallow suture; inner margin with tiny single spine; apically with four or five crenulated teeth (cr-t). Telopoditomere 4 short; tip round, with two conspicuous spines. All telopoditomeres covered by long sparse setae, except for basal part of telopoditomere 1 and tip of telopoditomere 2.

Posterior telopods (Figs 11A–E, 11G, 23I, 23J). Consisting of four telopoditomeres. First telopoditomere rectangular; stout; slightly wider than long. Telopoditomere 2 large and wide. Process of telopoditomere 2 (= immovable finger) long and swollen, twice as long as wide; slightly longer than a combination of telopoditomeres 3 and 4 (= movable finger); rounded apically; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; twice as long as wide; inner margin with a large membranous ledge and single long spine; posteriorly with a row of 11–13 crenulated teeth (cr-t). Telopoditomere 4 quite short; 3.5 × shorter than telopoditomere 3; twice as long as wide tip; inner margin with two long spines located on membranous ledge. Telopoditomeres 1 and 2 sparsely setose on anterior surface, glabrous on posterior surface. Telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns densely setose; slightly attenuate near tip.

Female sexual characters (Fig. 10C). Vulva large, sparsely setose; covering almost 1/3 of coxa; located mesoventrally; mesally reaching to base of prefemur. Operculum (op) large; well-rounded; with rounded tip. Bursa (bu) wide; fused; separated from operculum by shallow triangular groove. Apical part of coxa 2 without coxal process.

Noticeable variations occur in colouration and patterns of tergites. Most specimens display two yellow patches on dorsal tergites, typically semicircular or rectangular in shape (Fig. 7A, E). However, in some individuals, these patches may fade to a paler hue or completely absent (Fig. 7A, H).

The Thai specimens differ from the original description by Wesener (2019) in some morphological features. They have a greater range of body sizes, with males usually being smaller and females slightly larger, and they vary more in width and height. The tergites feature triangular yellow patches instead of the bright green of the type material. The aberrant ocellus of the Thai specimens is situated close to the brim of the antennal groove rather than inside. The number of apical sensory cones varies more widely and is greater in female Thai specimens (males 45–83; females 41–50). In the original description, the posterior margin of the endotergum was flat, but in Thai specimens, it was modified. The tegument of Thai specimens is dull and densely covered in golden setae, in contrast to the type specimens, which have a smooth, shiny, and glabrous surface (T. Wesener, pers. comm., re-examination of the type material).

In contrast to the type specimens, the paratergites are more noticeably protruding posteroventrad, and the thoracic shield comprises 5–8 keels. The legs of the Thai specimens differ slightly from what was originally described. Thai specimens possessed 12–16 small triangular spines on their femurs, while no spines were mentioned in the original description. Because these spines are minute and the original description was based on light microscopy only, their absence from Wesener (2019) most probably reflects the limits of that method rather than a genuine difference between the populations. The tarsus has somewhat reduced number of ventral and apical spines and is correspondingly shorter (2.5 × versus 3.5 × broad). In contrast to the original description, females have a smaller vulva that only covers one-third of the coxa, and the subanal plate is narrowly pointed rather than well-rounded. In males, the gonopore remains similar, but the anterior telopods differ by telopoditomere 4 with crenulated teeth. The immovable fingers of posterior telopods of Thai specimens are slender with 11–13 crenulated teeth, whereas those of the type specimens bear 11. Overall, the Thai specimens show consistent differences in body size, colour pattern, tegument texture, setation, legs, and telopod morphology, suggesting large intraspecific variation from the originally described population.

Despite this obvious variation, the male anterior and posterior telopods, the principal species-diagnostic structures in Zephronia, are indistinguishable between the Thai and Lao material. The Thai sequences cluster with the topotypic sequence MK330977 with maximal support (BS = 100, PP = 1.00) at a divergence of 4.88–5.95%, below the lowest interspecific distance recovered in this study (8.68%). We therefore treat the Thai population as a geographically divergent population of Z. laotica, while acknowledging that denser sampling in Laos and nuclear markers may reveal cryptic species-level structure.

Zephronia laotica is currently recorded only from the lower northeastern region of Thailand, specifically Si Sa Ket Province (Fig. 24). This species is typically found during the daytime in agricultural habitats such as durian orchards and rubber plantations. Specimens from durian orchards were found buried just below the soil surface, while those from rubber plantations were observed living on the surface beneath the leaf litter or decayed wood (Fig. 7J, K).

Holotype • ♂ (MZKKU-MYR0021); Thailand, Phetchabun Province, Bueng Sam Phan District, Nimit Sat Cha Tham Temple; 15°49'16.8"N, 100°55'03.9"E; ca 204 m a.s.l.; 3 September 2023; leg. C. Wilaisorn and MZKKU students. Paratypes. • 4 ♂♂ 4 ♀♀ (MZKKU-MYR0022); same data as for holotype; • 1 ♂ 1 ♀ (CUMZ-MYR0041); same data as for holotype.

The position of the Tömösváry’s organ located at the brim rather than inside the antennal groove (Fig. 13B, C), identifies Z. tamarindina sp. nov. as a member of the Zephronia s.s. species group. Z. tamarindina sp. nov. has an orangish brown body colour in adults and olive-greenish brown colour in juveniles, and differs from all other Zephronia s.s. species by the following combination of characters: in the anterior telopods, the process of telopoditomere 2 is broad and only slightly shorter than the combined length of telopoditomeres 3 and 4 (Figs 16C, 23K, 23M); telopoditomere 3 of the anterior telopods is distinctly widened (Figs 16C, 16F–H, 23K–M); and in the posterior telopods, telopoditomere 4 is strongly curved toward the immovable finger (Figs 16A–D, 23N, 23O). Males possess a conspicuous membranous process on the coxa of leg-pair 2 (Fig. 15B), a feature absent in all species except males of Z. enghoffi, Z. golovatchi and Z. sukhothaiensis. Z. tamarindina sp. nov. can be distinguished from the first two species by having only one row of marginal bristles in the midbody endotergum (two rows in Z. enghoffi and Z. golovatchi), and by the tip of the longest bristle being only half the length of the outer area (Fig. 22E, F), whereas in Z. enghoffi and Z. golovatchi the longest bristles project beyond the posterior margin. Z. tamarindina sp. nov. differs from Z. sukhothaiensis in the process of telopoditomere 2 of posterior telopods longer than telopoditomere 3+4 (while that of Z. sukhothaiensis is slightly shorter). Genetic divergence of COI sequences between Z. tamarindina sp. nov. and other Zephronia species ranged from 10.81 to 22.07%.

Measurements. Male holotype; body length = 18.6 mm; width (broadest), of thoracic shield = 9.5 mm, of tergite 7 = 10.5 mm; highest of thoracic shield = 6.1 mm, of tergite 7 = 7.8 mm. Males: body length = 15.0–22.5 mm; width (broadest), of thoracic shield = 7.3–11.7 mm, of tergite 7 = 7.5–12.3 mm; highest of thoracic shield = 5.8–7.6 mm, of tergite 7 = 6.9–8.8 mm. Females: body length = 14.8–26.2 mm; width (broadest), of thoracic shield = 7.1–12.6 mm, of tergite 7 = 6.6–13.7 mm; highest of thoracic shield = 4.8–8.7 mm, of tergite 7 = 8.8–10.0 mm.

Colouration (Fig. 12A–F). Live adult specimens with orangish brown body colour, juveniles olive-greenish brown. Head and collum olive green. Thoracic shield and tergites brown, with pale brown posterior bands (juveniles with two pale yellow rectangular dorsal patches per tergite); paratergites olive green or orangish brown. Roll-up form with a dark brown stripe on dorsal surface of tergites. Anal shield orangish brown with pale posterior brown band. Antenna green. Legs greenish brown. Venter pale brown. Specimens preserved in 95% ethanol changed to dark brown and some yellowish brown after 1.5 years of preservation.

Head (Fig. 13B–D). Trapeziform; broad; concave dorso-posteriorly; densely setose anteriorly, especially mouthparts. With 103–115 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.

Antennae (Fig. 13B, C, E, F). Apparently short and stout, emerging from sides of the head, covered by short setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 = 4 > 3 = 2 = 1. Antennomere 6 slightly flat, axe-shaped; with sensilla basiconica around apical disc. Apical disc with 65–88 apical cones in males, 55–67 apical cones in females.

Epipharynx (Fig. 13K). Apically with a single triangular central tooth (ct); with a conspicuous long and slender inner tooth mesally; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).

Gnathochilarium (Fig. 13G–J). Lamellae linguales (ll) oval; apically concave; with dense and long setae. Central pads (cp) modified; with two types of sensory cones (sc); first small, without tubercle apically, second larger with a concave pad apically containing a single internal tubercle. Stipites (st) large, with dense and long setae; located laterally to lamellae linguales. Mentum (me) broad, fused; with dense setae. Lateral palpi inconspicuous. Inner palpi (ip) with numerous sensory cones (sc); located in single field, each cone concave apically and containing a single internal tubercle.

Mandibles (gnathal lobe) (Fig. 13L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 5–6 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small slender teeth. Molar plate (mp) relatively flat, with shallow fringe. Condylus (co) conspicuous, apically with two ridges.

Tegument (Figs 12A–F, 14). Dull; collum, thoracic shield, tergites and anal shield covered by golden setae; each seta located in a small pit. Tergites and anal shield sparsely setose anteriorly and densely setose posteriorly.

Collum (Fig. 13A). Subsemicircular; lateral margin with a few long setae.

Thoracic shield. Anterior margin with a shallow canal covered by numerous long setae; with 5–9 conspicuous keels.

Midbody tergite (Fig. 14A–C). Dorso-anterior margin with a row of oval circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.

Anal shield (Fig. 14E–G). Slightly sexually dimorphic; females well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from margin by a row of crenate barriers. Underside with a dark locking carina; as long as those of tergites. Densely setose on both underside and upperside.

Endotergum of thoracic shield and midbody tergite (Fig. 22E, F). Thoracic shield slightly different from midbody tergite. Posterior margin (pm) of both thoracic shield and midbody tergite flat, unmodified. Outer area (oa) of both thoracic shield and midbody tergite with small denticles. Marginal bristles of both thoracic shield and midbody tergite arranged in one row; bristle quite short; tips of longest bristles half-length of outer area and not reaching to posterior margin. Middle area (ma) of thoracic shield with a row of oval cuticular impressions (cp); distance between each impression as half as the length of individual diameter. Middle area of midbody tergite with a row of cuticular impressions; distance between each impression as long as individual diameter. Inner area (ia) of thoracic shield and midbody tergite with a few setae.

Pleurite (laterotergite) (Fig. 14H, I). Densely setose. First pleurite triangular; boomeranglike; reaching towards paratergite. Pleurite 2 wider than pleurite 1; tip obtuse. Pleurites 3–12 rectangular.

Subanal plate of female (Fig. 14D). Densely setose; wide; triangular; tip truncated.

Stigmatic plates (Fig. 15A). First stigmatic plate subtriangular; quite slender; flat antero-posteriorly; apex round, curving towards coxa. Second stigmatic plate in both sexes swollen; weakly curved.

Legs (Fig. 15). All podomeres densely setose. Coxa (cx) large; as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with conspicuous processes. Prefemur stout; with short ridge (rdg); apico-mesally without projection. Femur (fe) wide and long, 1.5 × longer than prefemur; with conspicuous ridge; apico-mesally with a small projection; mesal margin dentate, with 6–8 small triangular microscopic spines (sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first two leg-pairs without an apical spine; leg-pair 1 with two or three ventral spines; leg-pair 2 with four or five ventral spines; leg-pair 3 with 6–10 ventral spines and one or two apical spines; leg pair 4 with 8–10 ventral spines and two or three apical spines; leg pairs 5–19 with 8–11 ventral spines and 3–5 apical spines; leg pair 20 and 21 with 7–9 ventral spines and three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal, with small notch at base.

Male sexual characters (Fig. 15B). Gonopore quite small; covered by a divided, triangular sclerotised plate. Apical part of coxa 2 with membranous process (Mp).

Anterior telopods (Figs 16A, 16C, 16F–H, 23K–M). Consisting of four telopoditomeres. First telopoditomere conspicuous; rectangular; longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; only slightly shorter than combination of telopoditomeres 3 and 4 (= movable finger); clearly seen in posterior view, strongly curved toward movable finger; inner margin with a single membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 wide; 2 × longer than telopoditomere 4; clearly demarcated from telopoditomere 4 by shallow suture; inner margin with single inconspicuous spine; apically with six or seven crenulated teeth (cr-t). Telopoditomere 4 very short; tip obtuse, with two spines. All telopoditomeres densely setose, except for basal part of telopoditomere 1 and of immovable finger of telopoditomere 2.

Posterior telopods (Figs 16A–E, 23N, 23O). Consisting of four telopoditomeres. First telopoditomere broad; slightly wider than long. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) long; 2 × longer than wide; longer than a combination of telopoditomeres 3 and 4 (= movable finger); apically round; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long and slender; 2.5 × longer than wide; with a large membranous ledge and single long spine at inner margin; posteriorly with a row of 14–20 crenulated teeth (cr-t). Telopoditomere 4 short; 3 × shorter than telopoditomere 3; twice as long as wide; strongly curved toward the immovable finger; inner margin with two long spines located on a membranous ledge. Telopoditomere 1 covered by long setae. Anterior surface of telopoditomere 2 with a few setae but glabrous in posterior one. Inner margin of immovable finger and telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns densely setose; swollen at base, slightly attenuate near tip.

Female sexual characters (Fig. 15C). Vulva large; sparsely setose; covering almost half of coxa; located at mesal margin; extending mesally to base of prefemur. Operculum (op) large; rectangular; mesal margin slightly concave; tip round. Bursa (bu) fused; heart-like; separated from operculum by a narrow triangular groove. Apical part of coxa 2 without coxal process.

The variation in colouration of paratergites was observed, with most specimens exhibiting an olive green colour, while some appeared orangish brown. Juveniles and smaller individuals typically showed olive greenish-brown colouration with rectangular patches on tergites. A distinctive feature of this species is the conspicuous triangular membranous process present on the coxae of male leg-pair 2 (Fig. 15B).

Zephronia tamarindina sp. nov. is currently known only from its type locality in Phetchabun Province and is thus considered endemic to this area (Fig. 24). The species was encountered during daytime on a rainy day within a dipterocarp forest, characterised by limestone terrain (Fig. 12G, H). Most specimens were observed moving on the ground amid gravel with sparse leaf litter.

The name is an adjective that derives from Tamarindus (tamarind), an important fruit cultivated in Phetchabun Province, the type locality. The name is treated as a feminine adjective in reference to the species body colouration, which changes from pale olive green in juveniles to a darker orangish brown in adults, resembling the ripening process of tamarind fruit from green to brown.

Holotype • ♂ (MZKKU-MYR0023); Thailand, Phitsanulok Province, Wat Bot District, Ban Nam Kob; 16°59'43.6"N, 100°23'34.0"E; ca 95 m a.s.l.; 6 August 2024; leg. C. Wilaisorn and MZKKU students. Paratypes. • 29 ♂♂ 25 ♀♀ (MZKKU-MYR0024), same data as for holotype; • 1 ♂ 1 ♀ (CUMZ-MYR0042); same data as for holotype; • 1 ♂ 1 ♀ (NHMUK); same data as for holotype; • 1 ♂ 1 ♀ (NHMD); same data as for holotype; • 1 ♂ 1 ♀ (NHMW); same data as for holotype; • 2 ♂♂ 2 ♀♀ (ZFMK); same data as for holotype.

• 13 juveniles (MZKKU), same data as for holotype; • 29 ♂♂, 13 ♀♀ (MZKKU); Thailand, Phitsanulok Province, Wat Bot District, Khao Bo Ma Viewpoint; 17°18'20.3"N, 100°26'29.2"E; ca. 216 m a.s.l.; 10 July 2024; leg. C. Wilaisorn, R. Srisonchai and MZKKU students; • 7 ♂♂ 4 ♀♀ (MZKKU); Thailand, Nakhon Sawan Province, Takhli District, Buddhawajana Dhamma Retreat; 15°17'51.7"N, 100°22'24.6"E; ca 70 m a.s.l.; 31 July 2023; leg. C. Wilaisorn, R. Srisonchai, and MZKKU students.

The position of the Tömösváry’s organ is located at the brim rather than inside the antennal groove (Fig. 18B, C), placing Z. triforma sp. nov. within the Zephronia s.s. species group. Z. triforma sp. nov. exhibits a distinctive range of live body colour patterns, forming three morphotypes: (1) males with greyish brown colouration and dark brown freckles, (2) females with reddish brown colouration, and (3) both sexes with a brownish emerald-green colouration. Beyond these colour traits, Z. triforma sp. nov. differs from other members of the Zephronia s.s. group by the following combination of characters: anterior telopods with the process of telopoditomere 2 broad; telopoditomere 4 very short with a tapering tip (Figs 21C, 21F, 23P–R); operculum with a concave mesal margin and a dull tip (Fig. 20C); endotergum with a flat, regular, posterior margin bearing two rows of marginal bristles, the longest bristles not projecting beyond the posterior margin, one row of circular cuticular impressions, and an inner area lacking setae (Fig. 22G, H). Genetic divergence between Z. triforma sp. nov. and other Zephronia species ranged from 10.81 to 22.83% based on 658 bp COI sequences.

Measurements. Male holotype; body length = 17.9 mm; width (broadest), of thoracic shield = 10.6 mm, of tergite 7 = 11.1 mm; highest of thoracic shield = 5.8 mm, of tergite 7 = 6.5 mm. Males: body length = 15.2–26.2 mm; width (broadest), of thoracic shield = 8.7–11.03 mm, of tergite 7 = 9.2–15.2 mm; highest of thoracic shield = 5.2–8.7 mm, of tergite 7 = 5.3–9.7 mm. Females: body length = 18.2–30.8 mm; width (broadest), of thoracic shield = 8.9–15.2 mm, of tergite 7 = 9.6–15.9 mm; highest of thoracic shield = 5.4–9.2 mm, of tergite 7 = 5.1–11.1 mm.

Colouration (Fig. 17A–I). Living specimens of Phitsanulok population of greyish brown colour with dark brown freckles in males; dark reddish-brown colour without freckles in females. Head and collum dark brown. Thoracic shield and tergites greyish brown in males, dark reddish-brown in females. Both sexes with dark brown posterior bands on tergites, and with a dark stripe on middle area of tergites, clearly seen when rolled up. Anal shield orangish brown on posterior margin. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol changed to dark brown after 1.5 years of preservation.

Living specimens of Nakhon Sawan population with a brownish emerald-green body. Head and collum brownish emerald green. Thoracic shield and tergites dark green with dark brown posterior. Anal shield emerald green with pale brown on posterior margin. Antenna and legs green. Venter pale brown. Specimens in 95% ethanol faded to dark brown after 1.5 years of preservation.

Head (Fig. 18B–D). Trapeziform, broad, round; densely setose anteriorly especially mouthparts. With 88–112 ommatidia (ocelli). Aberrant ommatidium situated at brim of antennal groove. Tömösváry’s organ separated from eye field and located between base of antenna and ommatidia. No sclerotised ridge between antennal groove and ommatidia.

Antennae (Fig. 18B, C, E, F). Short and sturdy, emerging from both sides of head, covered by noticeable long setae; last antennomere reaches back posteriorly to leg pair 2. Lengths of antennomeres in descending order: 6 > 5 = 4 > 3 = 2 > 1. Antennomere 6 flattened, axe-shaped; with sensilla basiconica around apical disc. Apical disc shallowly concave; with 48–88 apical cones in males, and 43–77 apical cones in females.

Epipharynx (Fig. 18K). Apically with a single obtuse central tooth (ct); in the middle with a conspicuous and swollen inner tooth; inner area with a single row of triangular fringed spines (rsp); outer area with several pointed and long external teeth (et).

Gnathochilarium (Fig. 18G–J). Lamellae linguales (ll) rounded, apically concave, densely setose. Central pads (Cp) modified, with two types of sensory cones (sc), first small without a tubercle apically, second larger with a concave pad apically containing a single internal tubercle. Stipites (st) large and thick, with densely long setae; located laterally to lamellae linguales. Mentum (me) broad and fused, densely setose. Lateral palpi inconspicuous. Inner palpi (ip) with numerous cylinder sensory cones (sc) located in single field, each cone concave apically and containing a single internal tubercle.

Mandibles (gnathal lobe) (Fig. 18L). With single undivided external tooth (Et) and 3-combed inner tooth (3it). With 6–7 rows of pectinate lamellae (pl). Inner area (Ia) with several rows of small, slender teeth. Molar plate (mp) relatively flat, with shallow fringe. Condylus (co) conspicuous; apically with two ridges.

Tegument (Figs 17A–I, 19). Dull; collum, thoracic shield, tergites and anal shield densely covered by golden setae; each seta emerged from a pit. Tergites and anal shield sparsely setose anteriorly and densely setose posteriorly. Posterior rim with bare setae on both dorsal and ventral sides.

Collum (Figs 18A). Subsemicircular; lateral edges triangular, with sparse setae.

Thoracic shield. Anterior margin with shallow canal covered by numerous long setae. Phitsanulok population with 3–6 small keels. Nakhon Sawan population with 6–10 conspicuous keels.

Midbody tergite (Fig. 19A–C). Dorso-anterior margin with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove, separated from anterior margin by a row of crenate barriers. Tips of paratergites projected posteroventrad.

Anal shield (Fig. 19E–G). Slightly sexually dimorphic; female anal shield well-rounded, males rectangular and slender. Anteriorly with a row of circular impressions and numerous small tubercles. Inner area with a shallow groove; separated from margin by a row of crenate barriers. Underside with a dark locking carina; twice as long as those of tergites. Densely setose on both underside and upperside.

Endotergum of thoracic shield and midbody tergite (Fig. 22G, H). Thoracic shield quite similar to midbody tergite. Posterior margin (pm) regularly flat. Outer area (oa) with several small denticles. Marginal bristles arranged in two rows, tips of longest bristles of Phitsanulok specimens two-thirds length of outer area (one-third in Nakhon Sawan specimens) and not projecting above margin. Middle area (ma) with a row of circular cuticular impressions (cp); distance between each impression twice as long as individual diameter in thoracic shield, and 3 × as long as individual diameter in midbody tergite. Cuticular impressions of thoracic shield shallower than those of midbody tergite. Inner area (ia) without tubercles or setae.

Pleurite (laterotergite) (Fig. 19H, I). Densely setose. First pleurite boomeranglike with pointed edge, reaching towards paratergite. Pleurite 2 widened. The remaining flat, rectangular.

Subanal plate of female (Fig. 19D). Densely setose; wide; semicircular; apical margin weakly concave, narrow.

Stigmatic plates (Fig. 20A). First stigmatic plate quite slender, flat ante-posteriorly; apex broadly round, curved towards coxa. Second stigmatic plate in both sexes broad, weakly curved.

Legs (Fig. 20). All podomeres densely setose. Coxa (cx) large, as long as length of prefemur (pre); first and second leg-pairs without coxal process; leg-pairs 3–21 with large and slightly serrated processes. Prefemur plump; with short ridge (rdg); apico-mesally with a very weak projection; mesal margin with one or two small triangular microscopic spines (sp). Femur (fe) prolonged; 1.5 × longer than prefemur; with conspicuous long ridge; apico-mesally with a strong projection; mesal margin dentated, with 10–12 small triangular spines. Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs long and slender, as long as length of femur+postfemur; first two leg-pairs without an apical spine; leg-pair 1 with two or three ventral spines; leg-pair 2 with four or five ventral spines; leg-pair 3 with 5–7 ventral spines and 1–3 apical spines; leg pair 4 with 7–10 ventral spines and three or four apical spines; leg pairs 5–19 with 9–12 ventral spines and 3–5 apical spines; leg pair 20 and 21 with 7–10 ventral spines and two or three apical spines. In leg 10, femur 1.5 ×, tarsus 3 × longer than wide. Claw normal; with notch at base.

Male sexual characters (Fig. 20B). Gonopore surrounded by long setae; covered with a divided, triangular sclerotised plate. Apical part of coxa 2 without membranous process.

Anterior telopods (Figs 21A, 21C, 21F, 21G, 23P–R). Consisting of four telopoditomeres. First telopoditomere broad; slightly longer than wide. Telopoditomere 2 large. Process of telopoditomere 2 (= immovable finger) broad; shorter than combination of telopoditomeres 3 and 4 (= movable finger); located posteriorly; clearly seen in posterior view; tapering apically; strongly curved toward movable finger; inner margin with a membranous lobe and numerous sclerotised spots (scl-s). Telopoditomere 3 slender; almost twice as long as telopoditomere 4; demarcated from telopoditomere 4 by weak suture; inner margin with single conspicuous spine; apically with 2–5 crenulated teeth (cr-t). Telopoditomere 4 very short; tapering tip, with two long spines. All telopoditomeres covered by long sparse setae, except for basal part of telopoditomere 1 and tip of telopoditomere 2.

Posterior telopods (Figs 21A–E, 23S, 23T). Consisting of four telopoditomeres. First telopoditomere rectangular; longer than wide. Telopoditomere 2 large and stout. Process of telopoditomere 2 (= immovable finger) long and slender, 2.5 × longer than wide; slightly longer than a combination of telopoditomeres 3 and 4 (= movable finger); weakly tapering apical; slightly curved; inner margin with two membranous lobes (ml) and numerous conspicuous sclerotised spots (scl-s). Telopoditomere 3 long; 3 × longer than wide; with a large membranous ledge and single long spine at inner margin; posteriorly with a row of 12–17 crenulated teeth (cr-t). Telopoditomere 4 short; 4 × shorter than telopoditomere 3; twice as long as wide, slightly tapering apically; inner margin with two long spines located on membranous ledge. Telopoditomere 1 and 2 mostly covered by setae on anterior surface, glabrous on posterior surface. Telopoditomere 3 sparsely setose. Telopoditomere 4 glabrous. Inner horns sparsely setose; base wide; sharp-edged tips; slightly curved posteriorly.

Female sexual characters (Fig. 20C). Vulva large, sparsely setose; covering almost half of coxa; located mesoventrally; extending mesally to base of prefemur. Operculum (op) slender; rectangular; with slightly concave mesal margin; tip of operculum dull. Bursa (bu) large; fused; separated from operculum by triangular groove. Apical part of coxa 2 without coxal process.

Notable sexual dimorphism is observed in the Phitsanulok specimens, in which adult males possess a greyish brown body with dark brown freckles, whereas adult females exhibit a reddish-brown body lacking freckles. Specimens from Nakhon Sawan Province differ in body colouration (brownish emerald-green) from those of Phitsanulok Province. The two populations also show slight morphological variation in marginal bristles of endotergum, the Phitsanulok specimens having bristles reaching two-thirds the length of the outer area, while those from Nakhon Sawan reach only one-third. These differences are accompanied by moderate but sub-specific genetic differentiation between the two populations (pairwise distances 5.02–5.63%), which remains well below the lowest interspecific distance recovered here (8.68%). Specimens from the type locality (Ban Nam Kob in Phitsanulok Province) were heavily infested with numerous small, white, phoretic deutonymphs of an unidentified mite, concentrated on the ventral surface, particularly legs (Fig. 20D, E).

Zephronia triforma sp. nov. is currently known only from the upper central region of Thailand, specifically Nakhon Sawan and Phitsanulok Provinces (Fig. 24). The specimens of populations from Phitsanulok Province were found during the daytime in dipterocarp forests, typically walking on the sandstone or sometimes hiding under the leaf litter (Fig. 17J). The individuals of the population from Nakhon Sawan Province were found in a dry deciduous forest characterised by sparse undergrowth, leaf litter, and rocky limestone terrain (Fig. 17K).

The species name is a Latin compound noun derived from tri- (three) and forma (form), referring to the three distinct morphotypes observed in the material used to describe the new species.